Dynamical signature of a domain phase transition in a perpendicularly magnetized ultrathin film

Abstract

Domain phases in ultrathin Fe/Ni/W(110) films with perpendicular anisotropy have been studied using the ac magnetic susceptibility. Dynamics on time scales of minutes to hours were probed by quenching the system from high temperature to the stripe phase region, and varying the constant rate of temperature increase as the susceptibility traces were measured. The entire susceptibility peak is observed to relax slowly along the temperature axis, with the peak temperature increasing as the rate of heating is decreased. This is precisely opposite to what would happen if this slow relaxation was driven by changes in the domain density within the stripe phase. The data are instead consistent with a simple model for the removal of a significant density of pattern defects and curvature trapped in the quench from high temperature. A quantitative analysis confirms that the relaxation dynamics are consistent with the mesoscopic rearrangement of domains required to remove pattern defects, and that the experiment constitutes a "dynamical" observation of the phase transition from a high temperature, positionally disordered domain phase to the low temperature, ordered stripe phase.

Dynamics of domain growth driven by dipolar interactions in a perpendicularly magnetized ultrathin film

“…The curve shifts to higher temperature with increasing R, since increasing R increases T n in eq. (15). (Note that the direction of this shift is opposite to that described in the previous section for the relaxation of topological pattern defects.)…”

Dynamics of topological defects in a two-dimensional magnetic domain stripe pattern

“…The experiments in ref. (20) provide further evidence to help resolve this ambiguity. The magnetic susceptibility was also measured while cooling, although the range of accessible cooling rates was not large enough to conduct a systematic study.…”

Monte Carlo simulation of the effects of higher-order anisotropy on the spin reorientation transition in the two-dimensional Heisenberg model with long-range interactions

“…The authors note that near to the SRT, quadratic coupling alone is not sufficient to account for this mixed behavior. Using AC susceptibility studies of striped phases in Fe/Ni films by Abu-Libdeh et al [36,37,57], have also indicated the presence of long time scale dynamics. By varying the order of anisotropy we wish to investigate the nature of the phase transition between the striped and in plane phases.…”

“…The width and mobility of stripes depends on temperature [35]. In particular these can systems display strong thermal memory, in which the domain configuration depend on the rate of heating or cooling [36,37]. Both the reorientation and stripe melting transitions have been studied analytically [38,39,40,41] and using Monte Carlo Simulation [42,43].…”